[Ocfs2-devel] [PATCH] ocfs2/dlm: fix umount hang

[Gechangwei]

Hi

During my recent test on OCFS2, an umount hang issue was found.
Below clues can help us to analyze this issue.

From the debug information, we can see some abnormal stats like only node 1 is in DLM domain map, however, node 3 - 9 are still
in MLE's node map and vote map.
The root cause of unchanging vote map I think is that HB events are detached too early!
That caused no chance of transforming from BLOCK MLE into MASTER MLE. Thus NODE 1 can't master lock resource even
other nodes are all dead.

To fix this, I propose a patch.

From 3163fa7024d96f8d6e6ec2b37ad44e2cc969abd9 Mon Sep 17 00:00:00 2001
From: gechangwei <ge.changwei at h3c.com>
Date: Thu, 17 Nov 2016 14:00:45 +0800
Subject: [PATCH] fix umount hang

Signed-off-by: gechangwei <ge.changwei at h3c.com>
---
 fs/ocfs2/dlm/dlmmaster.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 6ea06f8..3c46882 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -3354,8 +3354,6 @@ static void dlm_clean_block_mle(struct dlm_ctxt *dlm,
                spin_unlock(&mle->spinlock);
                wake_up(&mle->wq);

-               /* Do not need events any longer, so detach from heartbeat */
-               __dlm_mle_detach_hb_events(dlm, mle);
                __dlm_put_mle(mle);
        }
 }
--
2.5.1.windows.1


root at HXY-CVK110:~# grep P000000000000000000000000000000 bbb
Lockres: P000000000000000000000000000000   Owner: 255  State: 0x10 InProgress

root at HXY-CVK110:/sys/kernel/debug/o2dlm/7DA412FEB1374366B0F3C70025EB1437# cat dlm_state
Domain: 7DA412FEB1374366B0F3C70025EB1437  Key: 0x8ff804a1  Protocol: 1.2
Thread Pid: 21679  Node: 1  State: JOINED
Number of Joins: 1  Joining Node: 255
Domain Map: 1
Exit Domain Map:
Live Map: 1 2 3 4 5 6 7 8 9
Lock Resources: 29 (116)
MLEs: 1 (119)
  Blocking: 1 (4)
  Mastery: 0 (115)
  Migration: 0 (0)
Lists: Dirty=Empty  Purge=Empty  PendingASTs=Empty  PendingBASTs=Empty
Purge Count: 0  Refs: 1
Dead Node: 255
Recovery Pid: 21680  Master: 255  State: INACTIVE
Recovery Map:
Recovery Node State:


root at HXY-CVK110:/sys/kernel/debug/o2dlm/7DA412FEB1374366B0F3C70025EB1437# ls
dlm_state  locking_state  mle_state  purge_list
root at HXY-CVK110:/sys/kernel/debug/o2dlm/7DA412FEB1374366B0F3C70025EB1437# cat mle_state
Dumping MLEs for Domain: 7DA412FEB1374366B0F3C70025EB1437
P000000000000000000000000000000  BLK  mas=255 new=255 evt=0        use=1       ref=  2
Maybe=
Vote=3 4 5 6 7 8 9
Response=
Node=3 4 5 6 7 8 9
-------------------------------------------------------------------------------------------------------------------------------------
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